Char chiles over gas flame or under broiler until blackened on all sides. Enclose in plastic bag and let stand 10 minutes. Peel chiles. Starting at stem end, carefully cut one slit down length of each chile, leaving stems and tops intact if possible. Carefully remove seeds and veins from chiles.

Bake until chiles are heated through and sauce bubbles, about 25 minutes (about 40 minutes for refrigerated casserole).

Red Salsa

Makes about 2 cups

2 tablespoons vegetable oil

1 yellow onion, thinly sliced

2 cloves garlic, sliced

1 fresh jalapeno chili pepper, stemmed, seeded and thinly sliced

1 teaspoon salt, or to taste

2 cups canned plum tomatoes with their juices

In a saucepan over medium heat, warm the vegetable oil. Add the onion and saute until soft, about 10 minutes. Add the garlic, chili pepper and salt and cook for 2 minutes longer. Add the tomatoes and their juices and reduce the heat to low. Cook the tomatoes, stirring occasionally to break them up, until soft and the juices have reduced by half, 10-15 minutes.

Let cool slightly, then transfer to a blender. Puree until smooth, then strain through a sieve placed over a bowl. Set aside to cool completely for use as a table salsa. Or reheat gently over low heat to use hot. To store, cover tightly and keep in the refrigerator for up to 4 days or in the freezer for up to 1 month.